Effects of Inertia on Flow of Steam through Nozzles and Blading of Axial-flow Turbines

Abstract

A method is given for calculating the radial distribution of pressure in a steam turbine with long blades, the conditions for radial equilibrium, for continuity, and for energy balance being satisfied simultaneously. An example, illustrating the application of the method, shows that if there is pure impulse at the root of the blade, an appreciable degree of reaction may be reached at the outer end of the blade. It is shown that if the steam flow is to be parallel to the axis of the turbine then the variation of nozzle outlet angle with change of radius depends on the steam velocity at the inner radius. An alternative theoretical analysis of the problem is given which yields quickly the radial distribution of pressure where the nozzle outlet angle is uniform. This analysis is extended to give the degree of reaction at the blade tip in terms of that at the blade root. The paper concludes with a brief note showing that in geometrically similar turbines operating with the same blade speed, but different speeds of rotation, the radial distribution of pressure is the same.